package array;

// 实现自己的ArrayList
public class Array<E> {

    private E[] data;
    private int size;

    public Array(int capacity) {
        data = (E[]) new Object[capacity];
        size = 0;
    }

    public Array() {
        this(10);
    }

    public Array(E[] array) {
        data = (E[]) new Object[array.length];
        for (int i = 0; i < array.length; i++)
            data[i] = array[i];
        size = array.length;
    }
    // 获取数组中元素的个数
    public int getSize() {
        return size;
    }

    // 返回数组是否为空
    public boolean isEmpty() {
        return size == 0;
    }

    // 返回数组的容量
    public int getCapacity() {
        return data.length;
    }

    // 在index索引位置插入一个新元素e
    public void add(int index, E e) {
        if (index < 0 || index > size)
            throw new IllegalArgumentException("Add fail. Require index >=0 and index <= size");

        // 扩容
        if (size == data.length)
            resize(2 * data.length);

        for (int i = size - 1; i >= index; i--)
            data[i+1] = data[i];
        data[index] = e;
        size ++;
    }

    // 在所有元素前添加一个元素
    public void addFirst(E e) {
        add(0, e);
    }

    // 在所有元素后添加一个元素
    public void addLast(E e) {
        add(size, e);
    }

    // 获取index索引位置的元素
    public E get(int index) {
        if (index < 0 || index >= size)
            throw new IllegalArgumentException("Add fail. Require index >=0 and index <= size");

        return data[index];
    }

    public E getFirst() {
        return get(0);
    }

    public E getLast() {
        return get(size - 1);
    }

    // 修改index索引位置的元素为e
    public void set(int index, E e) {
        if (index < 0 || index >= size)
            throw new IllegalArgumentException("Add fail. Require index >=0 and index <= size");
        data[index] = e;
    }

    // 查找数组是否有元素e
    public boolean contains(E e) {
        for (int i = 0; i < size; i++) {
            if (data[i].equals(e))
                return true;
        }
        return false;
    }

    // 查找数组中元素e所在的索引, 如果不存在返回-1
    public int find(E e) {
        for (int i = 0; i < size; i++) {
            if (data[i].equals(e))
                return i;
        }
        return -1;
    }

    // 从数组中删除index位置元素, 返回被删除的元素
    public E remove(int index) {
        if (index < 0 || index >= size)
            throw new IllegalArgumentException("Add fail. Require index >=0 and index <= size");
        E ret = data[index];
        for (int i = index + 1; i < size; i++) {
            data[i - 1] = data[i];
        }
        size --;
        data[size] = null;

        if (size == data.length/4 && data.length/2 != 0)
            resize(data.length/2);
//        if (size == data.length/2)
//            resize(data.length/2);

        return ret;
    }

    // 从数组中删除第一个元素, 返回删除的元素
    public E removeFirst() {
        return remove(0);
    }

    // 从数组中删除最后一个元素, 返回删除的元素
    public E removeLast() {
        return remove(size - 1);
    }

    public void removeElement(E e) {
        int index = find(e);
        if (index != -1)
            remove(index);
    }

    public void swap(int i, int j) {
        if(i < 0 || i >= size || j < 0 || j >= size)
            throw new IllegalArgumentException("Index is illegal.");
        E e = data[i];
        data[i] = data[j];
        data[j] = e;
    }

    @Override
    public String toString() {
        StringBuilder res = new StringBuilder();
        res.append(String.format("Array: size = %d, capacity = %d\n", size, data.length));
        res.append("[");
        for (int i = 0; i < size; i++) {
            res.append(data[i]);
            if (i != size - 1)
                res.append(", ");
        }

        res.append("]");

        return res.toString();
    }

    private void resize(int newCapacity) {
        E[] newData = (E[]) new Object[newCapacity];
        for (int i = 0; i < size; i++)
            newData[i] = data[i];
        data = newData;
    }
}
